Minimally invasive lateral intervertebral fixation system, device and method

ABSTRACT

An intervertebral fixation device and system are disclosed, including a weight-bearing shell, first anchor, second anchor, and key. The shell includes a first and second opposing sidewalls, a keyway that extends between and through the first and second sidewalls, and a first axis of rotation and a second axis of rotation that extend between the first and second sidewalls. The first anchor is rotatably coupled to the shell about a first axis of rotation and is disposed in a first orientation. The second anchor is rotatably coupled to the shell about a second axis of rotation and is disposed in a second orientation. The second orientation is divergent from the first orientation. The key is configured to be disposed in the keyway to support the first anchor in a third orientation and the second anchor in a fourth orientation. The third orientation is divergent from the fourth orientation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/246,946, filed Oct. 7, 2008, which claims priority to U.S.Provisional Patent Application No. 60/998,376, filed Oct. 11, 2007, bothof which are incorporated herein by reference in their entireties.

BACKGROUND

1. Field

The present disclosure relates generally to spinal fusion devices. Morespecifically, example embodiments are directed a minimally invasivelateral intervertebral system, device and method.

2. Brief Discussion of Related Art

Articulations between bony vertebrae of a human spine—such as spinaldisks and facet joints—frequently deteriorate with age or trauma andbecome a source of pain. Spinal disk deterioration causes the spinaldisk to lose its normal consistency and volume, which facilitates thespinal disk to collapse and to cause abnormally painful motion acrossthe spinal disk within the spine. The abnormal motion across thedeteriorating spinal disk also increases the stresses on the facetjoints and accelerates their degeneration, further adding to theabnormally painful motion across the spinal disk of the spine.

A normal spinal disk is a cylindrical weigh-bearing fibrous structurewith a non-compressible viscous center. Due to its ability to deform,the spinal disk not only supports normal functional loads of the humanbody (e.g., load bearing) but also cushions and evenly distributes thestresses applied with body movement and positioning (e.g., loadsharing). The spinal disk articulates between the bony vertebrae—onevertebra above the spinal disk and one vertebra below the spinaldisk—through large surface area interfaces known as endplates. Anendplate is a thin (e.g., 1 mm-3 mm) and approximately round plate(e.g., 2 cm-4 cm in diameter) of dense bone and cartilage accounting fora majority of the vertebral load-bearing capacity.

Surgical treatment of spinal disk disorders has required fusion orelimination of movement across the abnormal spinal disk. This has beenaccomplished by allowing bone to grow between adjacent vertebrae andthrough a disk space of the abnormal spinal disk. In the foregoingsurgical treatment, the disk space of the abnormal disk is restored toits normal height by opening the disk space occupied by the spinal disk,which is removed, while also restoring a normal curvature of the spinedetermined by a differential height between the front and the back ofthe spinal disk between adjacent vertebrae (e.g., lordosis). Theforegoing restoration is commonly achieved by using a disk implant thatopens the space and allows for growth of bridging bone that fuses theadjacent vertebrae. The ultimate effectiveness of the disk implant isbased on: (i) its ability to restore and maintain normal curvature ofthe spine across the disk space; (ii) ease of its insertion and fixationwithin the disk space; (iii) its facilitation of bony fusion of theadjacent vertebrae; and (iv) its restriction of movement of the adjacentvertebrae in respect to the disk implant across the disk space.

Disk implants vary in shape but possess similar characteristics withupper and lower surfaces conforming to the shape of the vertebralendplates and vertical designs that aim to restore normal height of thecollapsed disk space and to restore normal curvature of spine. The diskimplants are sufficiently porous or hollow to allow bridging bone togrow through the disk implants and to bridge the adjacent vertebrae(e.g., bone fusion). These disk implants generally perform well withvertical load bearing and flexion of the spine. However, these diskimplants are not able to restrict movement between adjacent vertebraewhen the vertebrae are pulled apart, or subjected to extension andlateral bending. These disk implants further provide negligiblerestriction during translation (e.g., sliding motion) and rotation ofthe spine.

Some disk implants cut into or have protrusions directed into or throughthe endplates of the vertebrae. These protrusions penetrate theendplates and potentially create channels for bone growth, yet do notalter structural properties of the endplates. These protrusions furtherreduce the risk of extrusion of the disk implants from of the diskspace. The protrusions restrict translation of the disk implants but theprotrusions do not restrict extension and lateral bending. Thisnecessitates additional fixation or immobilization usually via posteriorpedicle screws.

One of the surgical techniques used to deliver the disk implant is aminimally invasive lateral approach. The minimally invasive lateralapproach utilizes a tubular access retractor to remove the spinal diskand to deliver a weight-bearing disk implant. The disk implant deliveredvia the lateral approach does not provide sufficiently rigid fixationand requires a further surgical procedure to provide posterior fixationof the disk implant. A current solution is to utilize a lateral platesecured with two screws. The lateral plate requires repetitive deliveryof multiple components through a small channel and provides a relativelysmall fixation advantage over the standalone disk implant. The abilityto provide sufficient fixation across the disk space through theminimally invasive lateral approach would eliminate the second surgicalprocedure.

SUMMARY

In a particular embodiment, an intervertebral fixation device isdisclosed. The device includes a weight-bearing shell, first anchor,second anchor and key. The weight-bearing shell includes a first andsecond opposing sidewalls, a keyway that extends between and through thefirst and second opposing sidewalls, and a first axis of rotation and asecond axis of rotation that extend between the first and secondopposing sidewalls.

The first anchor is rotatably coupled to the weight-bearing shell abouta first axis of rotation and is disposed in a first orientation inrelation to the weight-bearing shell. The second anchor is rotatablycoupled to the weight-bearing shell about a second axis of rotation andis disposed in a second orientation in relation to the weight-bearingshell. The second orientation is divergent from the first orientation.

The key is configured to be disposed in the keyway to support the firstanchor in a third orientation in relation to the weight-bearing shelland the second anchor in a fourth orientation in relation to theweight-bearing shell, the third orientation divergent from the fourthorientation.

In another particular embodiment, an intervertebral fixation system isdisclosed. The intervertebral fixation system includes an intervertebralfixation device. The intervertebral fixation device includes aweight-bearing shell, first anchor, second anchor and key. Theweight-bearing shell includes a first and second opposing sidewalls, akeyway that extends between and through the first and second opposingsidewalls, and a first axis of rotation and a second axis of rotationthat extend between the first and second opposing sidewalls.

The first anchor is rotatably coupled to the weight-bearing shell abouta first axis of rotation and is disposed in a first orientation inrelation to the weight-bearing shell. The second anchor is rotatablycoupled to the weight-bearing shell about a second axis of rotation andis disposed in a second orientation in relation to the weight-bearingshell. The second orientation is divergent from the first orientation.

The key is configured to be disposed in the keyway to support the firstanchor in a third orientation in relation to the weight-bearing shelland the second anchor in a fourth orientation in relation to theweight-bearing shell, the third orientation divergent from the fourthorientation.

Other aspects, advantages, and features of the present disclosure willbecome apparent after review of the entire application, including thefollowing sections: Brief Description of the Drawings, DetailedDescription, and the Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example shell of a minimally invasivelateral intervertebral fixation device;

FIG. 2 is an elevated side view of the example shell of FIG. 1;

FIG. 3 is a side view of the example shell of FIG. 1;

FIG. 4 is an elevated view of an example anchor of the minimallyinvasive lateral intervertebral fixation device;

FIG. 5 is a side translucent view of the example shell of FIG. 1 withplural example anchors concealed within the shell of FIG. 1;

FIG. 6 is a perspective translucent view of the shell of FIG. 1 withplural preloaded anchors in a concealed position within the shell ofFIG. 1;

FIG. 7 is a perspective view of a first embodiment of a minimallyinvasive lateral intervertebral system;

FIG. 8 is a perspective view of an example cylindrical key of minimallyinvasive lateral intervertebral system of FIG. 7;

FIG. 9 is a perspective view of a second embodiment of a minimallyinvasive lateral intervertebral system;

FIG. 10 is a perspective view of a cross-section of the secondembodiment of the minimally invasive lateral intervertebral system ofFIG. 9;

FIG. 11 is an elevated side view of a minimally invasive lateralintervertebral fixation device; and

FIG. 12 is an elevated side view of the minimally invasive lateralintervertebral fixation device of FIG. 11 with the plural exampleanchors in a locked and an extended position in relation to the shell ofFIG. 1 and securing a top endplate of a vertebra of a spine.

DETAILED DESCRIPTION

FIG. 1 is a perspective view 100 of an example shell 101 of a minimallyinvasive lateral intervertebral fixation device. The minimally invasivelateral intervertebral fixation device is illustrated in and describedwith reference to FIG. 11. The shell 101 is made of a material, such asa thermoplastic, a polymer, or a composite thereof, that is sufficientlyresilient to withstand stress or pressure of bodily movement andpositioning, while providing a degree of elasticity and also providingbiostablity and biocompatibility. The material should have a modulus ofelasticity that is comparable to bone. For example, the shell 101 may bemade of polyetheretherketone (PEEK), a thermoplastic with a Young'smodulus of elasticity of about 3.6 GPa and a tensile strength of about90 MPa. Also, because PEEK is resistant to both organic and aqueousenvironments, it is practical for the minimally invasive lateralintervertebral fixation device. Other materials that may be used includemetals, ceramics, medical plastics, coral, and other medicallyapplicable materials.

In various embodiments, the dimensions of the shell 101 areapproximately the following: the length of the shell 101 betweensidewalls 102, 104 is between about 45 mm and about 55 mm; the width ofthe shell 101 between the back wall 106 and the front wall 108 isbetween about 15 mm to about 22 mm; and the height of the shell betweentop and bottom surfaces 110, 122 is between about 8 mm and about 14 mm.It is noted that the foregoing dimensions are non-limiting and may beappropriately adjusted depending on different levels of the spine (e.g.,cervical, lumbar, thoracic) and depending on a particular person'sspinal anatomy.

The shell 101 includes sidewalls 102, 104, intermediate walls 146, 148and 150 between the sidewalls 102, 104, a back wall 106, a front wall108, and top and bottom surfaces 110, 112. One or more of the sidewalls102, 104 include a depression or a recess 114 to interface with anintroducer described herein below with reference to FIGS. 9 and 10. Asis described in reference to FIGS. 9 and 10, the introducer includes areciprocal protrusion to pressure fit the depression or recess 114 ofthe shell 101. While the sidewalls 102, 104, the intermediate walls 146,148, 150 and the top and bottom surfaces 110, 112 are generally flatsurfaces, the front wall 108 is a generally curve-shaped or arcuatesurface. The sidewalls 102, 104 and the intermediate walls 146, 148, 150include through holes 116 and 118 aligned at about the top and bottomsurfaces 110, 112, forming respective lengthwise channels through theshell 101 to receive and secure to the shell 101 plural anchors (shownin FIG. 4) by using respective pins (not shown) inserted through therespective channels. The respective lengthwise channels through theshell 101 provide respective axes of rotation proximate to the top andbottom surfaces 110, 112 of the shell 101. The through holes 116, 118are disposed proximate to the bottom and the top of the sidewalls 102,104 and the intermediate walls 146, 148, 150. The sidewalls 102, 104 andthe intermediate walls 146, 148, 150 also include respective key-shapedopenings 120, 138, 140, 142, 144 (hereinafter collectively referred toas a “keyway opening” or “keyway” 119) that provide access to the pluralanchors (shown in FIG. 6) to enable their rotation from a concealedposition within the shell 101 into an extended and fixed position inrelation to the shell 101 (shown in FIG. 1 I), using a wedge and acylindrical key (shown in FIGS. 7, 8 and 10). Each of the key-shapedopenings 120, 138, 140, 142, 144 is shaped identically to form thekeyway opening or keyway 119 between and through the sidewalls 102, 104.

The shell 101 includes plural openings 122, 124, 126 and 128 through thetop and bottom surfaces 110, 112, plural openings 130, 132, 134 and 136through the back wall 106 and the keyway opening 119 (e.g., pluralkey-shaped openings 120, 138, 140, 142 and 144) between and through thesidewalls 102, 104. Openings 122, 128 are about 5 mm-6 mm by about 10mm-12 mm, and openings 124, 126 are about 10 mm-12 mm by about 12 mm-16mm. Openings 130, 132, 134 and 136 may be of various sizes. Theforegoing plural openings form or define plural chambers (e.g., fourchambers) within the shell 101 to facilitate growth of bridging bonethrough the shell 101 of the minimally invasive lateral intervertebralfixation device. The inner chambers (e.g., innermost two chambers), asindicated by the openings 124, 126, also conceal plural anchors asillustrated in and described in reference to FIGS. 4-6. The outerchambers, as indicated by openings 122 and 128 do not conceal anyanchors and facilitate locking of the cylindrical key (shown in FIGS. 7,8 and 10).

FIG. 2 is an elevated side view 200 of the example shell 101 of FIG. 1.The keyway 119 (e.g., each of the key-shaped openings 120, 138, 140,142, 144) includes four portions 202, 204, 206 and 208. A centralapproximately round portion 202 approximates the circumference of thecylindrical key of FIG. 8, while portion 204 approximates the dimensionof plural protrusions about the circumference of the cylindrical key ofFIG. 8. Portions 202 and 204 allow the cylindrical key to move throughthe keyway 119 when the protrusions are aligned with portion 204 andrestrict movement of the cylindrical key when the protrusions of thecylindrical key are not aligned with portion 204. Portions 202, 204, 206and 208 of the keyway 119 facilitate access to and rotation of theplural anchors concealed within the shell 101 (shown in FIG. 6) fromtheir concealed position within the shell 101 into an extended and fixedposition in relation to the shell 101 (shown in FIG. 11), using thewedge and the cylindrical key (shown in FIGS. 7, 8 and 10).

FIG. 3 is a side view 300 of the example shell 101 of FIG. 1. Asillustrated in the side view 300, the sidewalls 102, 104 and theintermediate walls 146, 148, 150 gradually increase in height from theback wall 106 to the front wall 108, where the top and bottom surfaces110, 112 are angled with respect to a horizontal plane through a centerof the shell 101 (not shown) from the back wall 106 to the front wall108. To illustrate, in a particular embodiment, the shell 101 of theminimally invasive lateral intervertebral fixation device has a frontheight 304 of the front wall 108 that is higher than a back height 302in the back wall 106 to provide for a natural curvature of the cervicalor lumbar segments of the spine into which the minimally invasivelateral intervertebral fixation device may be implanted. The differencebetween the heights 302, 304 may be from about 2 mm to about 3 mm. In anexample embodiment, the back height 302 may be about 10 mm and the frontheight 304 may be about 12 mm. The heights 302, 304 may also be equal.As such, the angle may be varied (adjusting the heights 302, 304)between different levels of the spine (e.g., cervical, lumbar, thoracic)and between different people. The angle between the top surface 110 andthe horizontal plane (or the bottom surface 112 and the horizontalplane) may be between zero (0) and six (6) degrees, while a combinedangle between the horizontal plane and top and bottom surfaces 110, 112will most commonly be between three (3) and six (6) degrees depending onthe level of the spine and a particular person's spinal anatomy.

FIG. 4 is an elevated view 400 of an example anchor 401 of the minimallyinvasive lateral intervertebral fixation device. In a particularembodiment, the anchor 401 is made of a metal, such as titanium. Othermedically applicable metals may be employed. The anchor 401 is generallyc-shaped, having a generally straight base portion 402 that has aprotrusion 403, which provides a pivot for rotating the anchor 401 withthe wedge and the cylindrical key of FIGS. 7, 8 and 10. Additionally,the protrusion 403 is of a shape that approximates an edge of portion202 of the key-shaped openings 120, 138, 140, 142, 144 so that thecylindrical key better restricts the rotational movement of the anchor401. The base portion 402 includes a beveled or chamfered edge 404 tofacilitate the wedge in more easily advancing by and rotating the anchor401. A projection or arm portion 406 extends in a curve-shaped orarcuate direction from the base portion 402 and is adapted to secure anendplate of a vertebra of the spine. The projection 406 includes aleading pointed or sharp edge 408 adapted to penetrate the endplate of avertebra of the spine. A cylinder portion 410 is disposed transverse tothe base portion 402. The cylinder portion 410 includes through hole 411to secure the anchor 401 in the shell 101 (via pins described aboveinserted via through holes 116 or 118 and via through hole 411) and tofacilitate the anchor 401 in rotating about the axis of rotation at thetop or the bottom surfaces 110, 122 of the shell 101 via through hole411. In a particular embodiment, the through hole 411 is approximately1.5 mm and the projection 406 is a curve or arc that is approximately 10mm from the center of the through hole 411. The width 4 12 of the baseportion 402 is about half of the length 414 of the cylinder portion 410.In a particular embodiment, the width 412 is approximately 2.5 mm, thelength 414 is approximately 5.5 mm, and the height of the anchor 401from the base portion 402 to sharp edge 408 is about 12.5 mm. As isdescribed in detail below, an inner surface 416 of the anchor 401 is ofa shape that generally approximates the surface 110 or surface 112 ofthe shell 101 to provide weight-bearing support for the endplate of thevertebra that it will engage. The inner surface 416 may be adjusted toapproximate the surface 110 or surface 112 of the shell 101. The innersurface 416 includes a top edge 422 of the cylinder portion 410 thattransitions to a flat edge 420 of the base portion 402 and includes acontinuous inclining edge 418 that transitions the flat edge 420 to thearcuate projection or arm 406.

FIG. 5 is a side translucent view 500 of the example shell 101 of FIG. 1with plural example anchors 502, 504 concealed within the shell 101. Afirst anchor of the plural anchors 502 is positioned in a firstorientation and a second anchor 504 is positioned in a secondorientation in relation to the first anchor 502. More specifically, thesecond anchor 504 is positioned upside down in relation to the firstanchor 502. The disparate orientations of the anchors 502, 504 inrelation to one another enables the anchors 502, 504 to diverge throughthe openings 124, 126 in the top and bottom surfaces 110, 112 and toengage with endplates of respective vertebra of the spine (not shown).The disparate orientations of the anchors 502, 504 also facilitate thewedge and the cylindrical key of FIGS. 7, 8 and 10 to be insertedthrough portions 202, 204, 206 and 208, to engage the anchors 502, 504with the endplates of the respective vertebrae and to lock the anchors502, 504 in relation to the shell 101 and the respective vertebrae.

FIG. 6 is a perspective translucent view 600 of the shell 101 of FIG. 1with plural preloaded anchors 602-616 in a concealed position within theshell 101. The shell 101 conceals four (4) sets of disparately orientedanchors (602, 610), (604, 612), (606, 614), and (608, 616). Asillustrated in view 600, the length of the cylinder portion of eachanchor 602-616 (e.g., length 414 in FIG. 4) is approximately double ofthe width of the base portion (e.g., width 412 in FIG. 4) of each anchor602-616. This allows sufficient width of the cylinder to secure theanchors 602-616 to the shell 101 when the anchors 602-616 are extended(shown in FIG. 11), while mitigating the amount of space necessary forthe anchors 602-616. Anchors (602, 610) and (604, 612) diverge andextend through openings 124 in the top and bottom surfaces 110, 112,while anchors (606, 614) and (608, 616) diverge and extend throughopenings 126 in the top and bottom surfaces 110, 112.

FIG. 7 is a perspective view 700 of a first embodiment of a minimallyinvasive lateral intervertebral system 701. The minimally invasivelateral intervertebral system 701 includes an example wedge 702 and anexample cylindrical key 704 to interface with the example shell 101 andthe example plural anchors 602-616. The wedge 702 and cylindrical key704 are used to rotate the respective sets of anchors (602, 610), (604,612), (606, 614), and (608, 616), in order from the proximal to thedistal, from a concealed position within the shell 101 into an extendedand fixed position in relation to the shell 101 (shown in FIG. 11) toengage and secure endplates of respective vertebrae (not shown). Forexample, the wedge 702 is advanced forward (e.g., via portions 206 and208 of the keyway 119) to rotate a first proximal set of anchors (602,610) from the concealed position within the shell 101 to anintermediately rotated position in which the base portions of the set ofanchors (e.g., base portion 402 of FIG. 4) are disposed within thecentral portion (e.g., central portion 202 of FIG. 2) of the keyway 119(e.g., key-shaped opening 138 of FIG. 1). The wedge is similarlyadvanced from the sidewall 102 to the sidewall 104 to rotate therespective sets of the anchors into intermediately rotated positions. Inthe intermediately rotated position, the respective sets of anchors havebeen partially extended from the shell 101 through the openings (e.g.,openings 124, 126 of FIG. 1) in the top and bottom surfaces of shell 101(e.g., top and bottom surfaces 110, 112). The cylindrical key 704 isthen advanced forward, fully rotating the first proximal set of anchors(602, 610) and other sets of anchors (604, 612), (606, 614), and (608,616) into their fully extended positions in relation to the shell 101.

FIG. 8 is a perspective view 800 of the example cylindrical key 704 ofthe minimally invasive lateral intervertebral system of FIG. 7. Thecylindrical key 704 is made of a solid material, such as PEEK, toprovide the same biomechanical properties (e.g., resilience andelasticity) as the shell 101. The cylindrical key 704 includes acylinder portion 802 that includes a driving/rotating end 806 and aconical end 804. The driving/rotating end 806 includes a slit (shown inFIGS. 10-12) for a driver (not shown) that can drive and rotate thecylindrical key 704. The conical end 804 is offset from the center ofthe cylinder portion's 802 diameter to more easily rotate the anchorsfrom the intermediately rotated position to a fully extended position.The cylindrical key 704 further includes protrusions 808 and 810 thatfacilitate the cylindrical key 704 to be driven forward when theprotrusions 808, 810 are in a first orientation (e.g., protrusions 808,810 aligned with portion 204 of the keyway 119 shown in FIGS. 1 and 2).The protrusions further facilitate the cylindrical key 704 to secure therespective sets of anchors (e.g., 602-616 of FIG. 6) when theprotrusions 808, 810 are rotated via the driving/rotating end 812 into asecond orientation. More specifically, protrusion 810 may be engagedbetween sidewall 102 and intermediate wall 146, while protrusion 810 maybe engaged by intermediate wall 150, to support the sets of anchors(e.g., 602-616 of FIG. 6) in extended positions relative to the shell101 and to prevent the cylindrical key 704 from dislodging from theshell 101. In a particular embodiment, the length of the cylindrical key704 is about 50 mm and its cross-sectional diameter is about 8 mm. Inthis embodiment, the protrusions 808, 810 have a height of about 1.5 mmfrom the surface of the cylindrical key 704, where the protrusion 810has a length of about 6 mm and a width of about 5 mm, and the protrusion808 has a length of about 2 mm and a width of about 5 mm. In thisembodiment, the protrusion 808 includes a chambered or a beveled edgethat forms a part of the conical end 804.

FIG. 9 is a perspective view of a second embodiment of a minimallyinvasive lateral intervertebral system 900. The minimally invasivelateral intervertebral system 900 includes an example introducer 901,the shell 101 with plural anchors 602-616, the wedge 702, thecylindrical key 704 (shown in FIG. 10) and an extender/connector 907.The introducer 901 interfaces with the shell 101 and the cylindrical key704 to deliver and implant the shell 101, the plural anchors 602-616 andthe cylindrical key 704 (e.g., the minimally invasive lateralintervertebral fixation device) into a disk space between pluralvertebrae.

The introducer 901 is made of a rigid radiolucent material, such as aradiolucent metal. In various embodiments, the radiolucent metal may bealuminium, beryllium or other radiolucent metal. In a particularembodiment, the introducer 901 is approximately 20 cm long and has ahollow configuration that approximates the shell 101 shown in FIG. 1.The introducer includes a mating protrusion that pressure fits thedepression or recess 114 of the shell 101. The introducer 901 includes ahandle portion 902 and a swivel portion 904. To facilitate the minimallyinvasive lateral approach in delivering the minimally invasive lateralintervertebral fixation device (shown in FIG. 11), the plural anchors602-616 are preloaded within the shell 101, and the wedge 702 and thecylindrical key 704 are preloaded with the introducer 901. Alsopreloaded into the introducer 901 is the extender/connector 907 thatinterfaces the cylindrical key 704 to a driving/rotating tool (notshown), such as hexagonal screwdriver, to facilitate the cylindricalkey's 704 advancement and rotation in the shell 101 via thedriving/rotating end 806 of the cylindrical key 704. More specifically,the access to the cylindrical key 704 may be extended by theextender/connector 907, which may include a driving/rotating end and amating end that fits the driving/rotating end 806 of the cylindrical key704.

The handle portion 902 includes an opening 906 that receives protrusion810 of the cylindrical key 704, while the shell 101 receives theprotrusion 808 via opening 122 between sidewall 102 and intermediatewall 146 (shown in FIG. 1). Thus, the cylindrical key 704 temporarilysecures the introducer 901 to the shell 101 to facilitate the deliveryof the shell 101, the anchors 602-616 concealed therein, the cylindricalkey 704 and the extender/connector 907 into the disk space between thevertebrae (not shown). The swivel portion 904 includes a pivotingmechanism 905 that allows the swivel portion 904 to pivot via thepivoting mechanism 905 at about 90 degrees with respect to the handleportion 902. Striking a hammer on the swivel portion 904 that is inlinewith respect to the handle portion 902 is used to deliver or advance theshell 101, the plural concealed anchors 602-616 and the cylindrical key706 into position within the disk space between the vertebrae.

The swivel portion 904 includes an opening 903 that provides access tothe preloaded wedge 702 and the cylindrical key 704 via theextender/connector 907. More specifically, after positioning the shell101 in a proper orientation within the disk space by using theintroducer 901 in its inline position (e.g., the swivel portion 904 isextended in line with the handle portion 902 as shown in FIG. 9), theswivel portion 904 is pivoted (not shown) via the pivoting mechanism 905to expose the wedge 704 and the extender/connector 907 to thecylindrical key 704 via the opening 903. The wedge 702 is advancedforward into the shell 101 to rotate the anchors 602-616 into theirrespective intermediately rotated positions. The cylindrical key 704 isthen rotated about 90 degrees via the driving/rotating end 806 by usingthe extender/connector 907, until protrusions 808, 810 coincide withportion 204 of the keyway 119 (shown in FIG. 2), thereby unlocking thecylindrical key 704 from the introducer 901. The cylindrical key 704 isadvanced via the extender/connector 907 into the shell 101, rotating theanchors 602-616 into their respective final extended positions. Thecylindrical key 704 is then locked in the shell 101 by rotating thecylindrical key 704 via the extender/connector 907 back or forward sothat the protrusions 808, 810 do not coincide with portion 204 of thekeyway 119. The wedge 702 and the extender/connector 907 are removed andthe introducer 901 is removed from the disk space. Thus, the shell 101is secured to the endplates of the vertebrae via the anchors 602-616 andthe cylindrical key 704.

FIG. 10 is a perspective view 1000 of a cross-section of the secondembodiment of a minimally invasive lateral intervertebral system 900 ofFIG. 9. Perspective view 1000 illustrates cross-sections of the exampleintroducer 901 that interfaces with the example shell 101 and thecylindrical key 704 to deliver and implant the shell 101, the pluralanchors 602-616 and the cylindrical key 704 (e.g., minimally invasivelateral intervertebral fixation device). The perspective view 1000 alsoillustrates the preloaded anchors 602-616 in the shell 101, thepreloaded wedge 702, cylindrical key 704 and extender/connector 907within the introducer 901. The preloading of the foregoing elements viathe shell 101 and the introducer 901 facilitates the minimally invasivelateral approach in delivering and securing the minimally invasivelateral intervertebral fixation device (e.g., shell 101, anchors602-616, cylindrical key 704) within the disk space between vertebrae.

FIG. 11 is an elevated side view 1100 of a minimally invasive lateralintervertebral fixation device 1102. The minimally invasive lateralintervertebral fixation device 1102 is shown with plural anchors 602-616of FIG. 6 in an extended position in relation to the shell 101 ofFIG. 1. The plural anchors 602-616 are locked via the cylindrical key704, which may be advanced via the driving/rotating end 806 and rotatedvia a hexagonal recess 1104. In the extended and locked position, thebase portions of the plural anchors 602-616 (e.g., base portion 402) aresupported by the cylindrical key 704. The inner surfaces 416 of theplural anchors 602-616 generally approximate the surfaces 110 or 112 toprovide weight-bearing support for the endplates of the vertebrae.

FIG. 12 is an elevated side view 1200 of the minimally invasive lateralintervertebral fixation device 1102 of FIG. 11 with the plural exampleanchors 602-616 in a locked and an extended position in relation to theshell of FIG. 1 and securing a top endplate 1204 of a vertebra 1202 of aspine (not shown). For clarity, the minimally invasive lateralintervertebral fixation device 1102 is shown securing only one vertebra.It is noted, however, that the minimally invasive lateral intervertebralfixation device 1102 is inserted into a disk space between pluralvertebrae, one below and one on top of the minimally invasive lateralintervertebral fixation device 1102, and secures the plural vertebraevia the respective anchors 602-608 and 610-616 and cylindrical key 704.The minimally invasive lateral intervertebral fixation device 1102 isdisposed approximately centrally within the disk space between theplural vertebrae. The vertebra 1202 includes a top endplate 1204, abottom endplate 1208 and a central portion 1206. The endplates 1204,1208 consist of cortical bone, which is much harder and denser than thecancellous bone of the central portion 1206. Consequently, therespective anchors 602-608 and 610-616 hook and secure the respectiveendplates 1204 and 1208 of plural vertebrae. The inner surfaces 416 ofthe plural anchors 602-608 and 610-616 generally approximate the topsurface 110 or the bottom surface 112 to provide weight-bearing supportfor the endplates of the vertebra. Because the shell 101 and thecylindrical key 704 are made of the same material (e.g., PEEK) and theinner surfaces 416 of the plural anchors 602-608 and 610-616 approximatethe top and bottom surfaces 110, 112 of the shell 101, the minimallyinvasive lateral intervertebral fixation device 1102 providessubstantial weight-bearing capability and mitigates subsidence of the ofthe minimally invasive lateral intervertebral fixation device 1102 intothe vertebrae.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the principles defined hereinmay be applied to other embodiments without departing from the scope ofthe disclosure. Thus, the present disclosure is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope possible consistent with the principles and novel features asdefined by the following claims.

What is claimed is:
 1. An intervertebral fixation device, the devicecomprising: a weight-bearing shell including a first and second opposingsidewalls, a keyway that extends from and through a first opposingsidewall to and through a second opposing sidewall of the first andsecond opposing sidewalls, and a first axis of rotation and a differentsecond axis of rotation that are outside the keyway and extend from thefirst opposing sidewall to the second opposing sidewall of the first andsecond opposing sidewalls; a first anchor rotatably coupled to theweight-bearing shell about the first axis of rotation and disposed in afirst orientation in relation to the weight-bearing shell; a secondanchor rotatably coupled to the weight-bearing shell about the secondaxis of rotation and disposed in a second orientation in relation to theweight-bearing shell, the second orientation divergent from the firstorientation; and a key configured to be locked in the keyway supportingthe first anchor in a third orientation in relation to theweight-bearing shell and the second anchor in a fourth orientation inrelation to the weight-bearing shell, the third orientation divergentfrom the fourth orientation.
 2. The intervertebral fixation device ofclaim 1, wherein the first anchor includes an inner surface thatapproximates a top surface of the weight-bearing shell when supported bythe key, the top surface extending between the first and second opposingsidewalls.
 3. The intervertebral fixation device of claim 1, wherein thesecond anchor includes an inner surface that approximates a bottomsurface of the weight-bearing shell when supported by the key, thebottom surface extending between the first and second opposingsidewalls.
 4. The intervertebral fixation device of claim 1, wherein thefirst axis of rotation extends proximate to a top surface of theweight-bearing shell, the top surface extending between the first andsecond opposing sidewalls.
 5. The intervertebral fixation device ofclaim 1, wherein the second axis of rotation extends proximate to abottom surface of the weight-bearing shell, the bottom surface extendingbetween the first and second opposing sidewalls.
 6. The intervertebralfixation device of claim 1, wherein at least one anchor of the firstanchor and the second anchor comprises: a base portion configured to besupported by the key in relation to the weight-bearing shell; an armportion that extends in a curve-shaped direction from the base portionand is configured to penetrate and secure to a first vertebra or asecond vertebra; and a cylinder portion disposed transversely to thebase portion and configured to facilitate the at least one anchor inrotating about the first axis of rotation or the second axis ofrotation.
 7. The intervertebral fixation device of claim 6, wherein thebase portion comprises an inner surface that approximates a top surfaceof the weight-bearing shell or a bottom surface of the weight-bearingshell when supported by the key.
 8. The intervertebral fixation deviceof claim 6, wherein the cylinder portion comprises a through hole torotatably secure the at least one anchor in relation to theweight-bearing shell via a pin that extends along the first axis ofrotation or the second axis of rotation.
 9. The intervertebral fixationdevice of claim 1, wherein the first anchor rotates about the first axisof rotation through an opening in a top surface of the weight-bearingshell to the third orientation in relation to the weight-bearing shellas the key is advanced in the keyway.
 10. The intervertebral fixationdevice of claim 1, wherein the second anchor rotates about the secondaxis of rotation through an opening in a bottom surface of theweight-bearing shell to the fourth orientation in relation to theweight-bearing shell as the key is advanced in the keyway.
 11. Theintervertebral fixation device of claim 1, wherein the key includes acylindrical body, plural protrusions extending from the cylindrical bodyto lock the key in the weight-bearing shell, and a conical end tofacilitate rotation of the first anchor and the second anchor.
 12. Theintervertebral fixation device of claim 11, wherein the keyway includesa cylindrical first portion configured to receive the cylindrical bodyof the key and a second portion configured to receive the pluralprotrusions of the key as the key is advanced in the keyway.
 13. Anintervertebral fixation system, the system comprising: an intervertebralfixation device, the device including: a weight-bearing shell includinga first and second opposing sidewalls, a keyway that extends from andthrough a first opposing sidewall to and through a second opposingsidewall of the first and second opposing sidewalls, and a first axis ofrotation and a different second axis of rotation that are outside thekeyway and that extend from the first opposing sidewall to the secondopposing sidewall of the first and second opposing sidewalls; a firstanchor rotatably coupled to the weight-bearing shell about the firstaxis of rotation and disposed in a first orientation in relation to theweight-bearing shell; a second anchor rotatably coupled to theweight-bearing shell about the second axis of rotation and disposed in asecond orientation in relation to the weight-bearing shell, the secondorientation divergent from the first orientation; and a key configuredto be locked in the keyway supporting the first anchor in a thirdorientation in relation to the weight-bearing shell and the secondanchor in the fourth orientation in relation to the weight-bearingshell, the third orientation divergent from the fourth orientation. 14.The intervertebral fixation system of claim 13, wherein the systemcomprises a wedge to rotate the first anchor about the first axisthrough an opening in a top surface of the weight-bearing shell from thefirst orientation in relation to the weight-bearing shell to anintermediate orientation in relation to the weight-bearing shell. 15.The intervertebral fixation system of claim 14, wherein the first anchorrotates from the intermediate orientation to the third orientation inrelation to the weight-bearing shell as the key is advanced in thekeyway.
 16. The intervertebral fixation system of claim 13, wherein thesystem comprises a wedge further configured to rotate the second anchorabout the second axis through an opening in a bottom surface of theweight-bearing shell from the second orientation in relation to theweight-bearing shell to an intermediate orientation in relation to theweight-bearing shell.
 17. The intervertebral fixation system of claim16, wherein the second anchor rotates from the intermediate orientationin relation to the weight-bearing shell to the fourth orientation inrelation to the weight-bearing shell as the key is advanced in thekeyway.
 18. The intervertebral fixation system of claim 13, wherein thesystem comprises an extender to interface the key to a driving/rotatingtool.
 19. The intervertebral fixation system of claim 13, wherein thesystem comprises an introducer that interfaces the intervertebralfixation device to insert the intervertebral fixation device into a diskspace between plural vertebrae.
 20. The intervertebral fixation systemof claim 19, wherein the introducer includes a handle portion that hasan opening to receive a first protrusion of the key and theweight-bearing shell includes an opening to receive a second protrusionof the key to removeably lock the introducer to the weight-bearing shellusing the key.
 21. The intervertebral fixation system of claim 19,wherein the introducer includes a swivel portion configured to pivot inrelation to the handle portion.
 22. The intervertebral fixation systemof claim 19, wherein the system comprises a wedge that is preloaded intothe introducer, the wedge disposed proximately to the first anchor andthe second anchor.
 23. The intervertebral fixation system of claim 19,wherein the system comprises an extender that is preloaded into theintroducer, the extender engaging the key.
 24. The intervertebralfixation system of claim 23, wherein the system comprises a screwdriving/rotating tool configured to engage the extender to unlock thekey from the introducer, the screw driving/rotating tool engaged to theextender further configured to advance the key in the keyway to rotatethe first anchor and the second anchor in relation to the weight-bearingshell.
 25. The intervertebral fixation system of claim 23, wherein thescrew driving/rotating tool engaged to the extender is furtherconfigured to lock the key in the weight-bearing shell.